Oxidation stability is a major requirement for all industrial lubricants. The major cause of oxidative instability is the autoxidative breakdown of the hydrocarbons in the lubricants with the concomitant formation of acids and other undesirable oxygenated species as well as sludge. Such autoxidative breakdown is strongly catalyzed by traces of metal ions, especially copper and iron, which become solubilized when the lubricant comes in contact with metal surfaces. One way to control oxidation is to incorporate into the lubricant certain additives, called metal deactivators, which prevent these catalytic reactions from occurring. Metal deactivators generally work in two different ways; they form impervious films on the metal surface, thereby preventing dissolution of the metal ions, and hence are called "film forming" additives, or they form chelates with the solubilized metal ions, thus rendering them inactive as catalysts, and hence are called "soluble metal chelators". Examples of the use of metal deactivators to stabilize lubricating compositions can be found, for example, in U.S. Pat. Nos. 2,352,164 and 4,392,968.
It is an object of this invention to provide new and improved metal deactivators having superior performance over that of conventional metal deactivators.
It is also another object of the present invention to provide compositions containing a new metal deactivator.